[chromeos] Fix chromeos volume tests

chrome/test/functional/chromeos_volume.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import logging
 import os
 import subprocess
+import sys
 
 import pyauto_functional  # Must be imported before pyauto
 import pyauto
 
+sys.path.append('/usr/local')  # To make autotest libs importable.
+from autotest.cros import cros_ui
+from autotest.cros import cryptohome
+
 
 class ChromeosVolume(pyauto.PyUITest):
   """Test case for volume levels.
 
   Test volume and mute changes with different state like, login,
   lock, logout, etc...
   """
 
   def setUp(self):
     # We want a clean session_manager instance for every run,
-    # so restart session_manager now.
-    assert self.WaitForSessionManagerRestart(
-        lambda: subprocess.call(['pkill', 'session_manager'])), \
-        'Timed out waiting for session_manager to start.'
+    # so restart ui now.
+    cros_ui.stop(allow_fail=True)
+    cryptohome.remove_all_vaults()
+    cros_ui.start(wait_for_login_prompt=False)
     pyauto.PyUITest.setUp(self)
     self._initial_volume_info = self.GetVolumeInfo()
 
   def tearDown(self):
     self.SetVolume(self._initial_volume_info['volume'])
     self.SetMute(self._initial_volume_info['is_mute'])
     pyauto.PyUITest.tearDown(self)
 
+  def ShouldAutoLogin(self):
+    return False
+
   def _Login(self):
     """Perform login"""
     credentials = self.GetPrivateInfo()['test_google_account']
     self.Login(credentials['username'], credentials['password'])
     logging.info('Logged in as %s' % credentials['username'])
     login_info = self.GetLoginInfo()
     self.assertTrue(login_info['is_logged_in'], msg='Login failed.')
 
   def testDefaultVolume(self):
     """Test the default volume settings"""
@@ skipping 35 matching lines @@
     self.SetVolume(lock_volume['volume'])
     self.SetMute(lock_volume['is_mute'])
     self.UnlockScreen(self.GetPrivateInfo()['test_google_account']['password'])
     after_login = self.GetVolumeInfo()
     self.assertEqual(lock_volume, after_login,
         msg='Locking screen volume changes are not preserved')
 
 
 if __name__ == '__main__':
   pyauto_functional.Main()